gulagi ashish, ram manish, breyer christian

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The Role of Transmission Grid and Solar Wind Complementarity in Mitigatingthe Monsoon Effect in a Fully Sustainable Electricity System for India

Gulagi Ashish, Ram Manish, Breyer Christian

Gulagi, A., Ram, M., Breyer, C. (2020). Role of the transmission grid and solar windcomplementarity in mitigating the monsoon effect in a fully sustainable electricity system forIndia. IET Renewable Power Generation, vol. 14, iss. 2, pp. 254-262. DOI: 10.1049/iet-rpg.2019.0603

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10.1049/iet-rpg.2019.0603

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This paper is a postprint of a paper submitted to and accepted for publication in IET RenewablePower Generation and is subject to Institution of Engineering and Technology Copyright. Thecopy of record is available at the IET Digital Library.

IET Renewable Power Generation

Research Article

Role of the transmission grid and solar windcomplementarity in mitigating the monsooneffect in a fully sustainable electricity systemfor India

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ISSN 1752-1416Received on 21st May 2019Revised 17th October 2019Accepted on 5th November 2019doi: 10.1049/iet-rpg.2019.0603www.ietdl.org

Ashish Gulagi1 , Manish Ram1, Christian Breyer1

1School of Energy Systems, LUT University, Yliopistonkatu 34, Lappeenranta, Finland E-mail: [email protected]

Abstract: Various assessments have shown abundant renewable energy (RE) potential for India, especially solar. For a fullysustainable power system, monsoon presents an obstacle with the resultant decrease in solar resource availability. In this study,India is subdivided into ten regions, and these regions are interconnected via power lines. A 100% RE transition pathway inhourly resolution, until 2050, is simulated. The results from this paper indicate that the power system can overcome themonsoon hurdle by solar–wind complementarity and grid utilisation. Wind energy output increases in regions that have the bestwind conditions with 62% of the total wind energy generated in monsoon. Solar photovoltaic (PV) and grids can manage theunavailability of wind resources in some of the regions. There is a clear indication that imports increase during the monsoonperiod. The least affected regions such as India-Northwest (IN-NW) can transmit PV electricity to other regions via transmissiongrids. In the monsoon period, grid utilisation increases by 1.3% from the non-monsoon period to satisfy the respective demand.The two major exporters of electricity, IN-NW and India-South export about 43% of electricity in the monsoon period. Theseresults indicate that no fossil-based balancing is required in the monsoon period.

1 IntroductionThe Indian power sector is evolving rapidly to keep up with theeconomic growth and fast-changing socio-economic status of thecountry [1]. The increasing electricity consumption due to thegrowth in gross domestic product and government's aim to providereliable electricity to every individual has put tremendous pressureon the power sector. Currently, electricity generation is largelybased on fossil fuels, particularly coal. The increased use of coalhas consequently contributed to rapid growth in greenhouse gas(GHG) emissions in the past decades [2]. The power sector in Indiais one of the major contributors to GHG emissions [3]. The majordilemma that India faces today is prioritising its energy goals of alow carbon economy with reduced dependence on coal andincreasing renewable energy (RE) usage [2]. The power sectorneeds to evolve rapidly to keep up with local and global goals.

In the past few years, India has woken up to the issue of climatechange and pollution and its devastating effects [4]. In its INDC

commitment at COP21, India pledged to reduce GHG emissionsby 33–35% until 2030 in comparison with 2005 and 40% of thecountry's electricity would be generated from renewables such aswind and solar [5]. Commitment to the Paris Agreement willrequire utilising the available RE resources to achieve the requiredtargets. Assessments [6, 7, 8] have shown India has abundant REpotential, especially solar. With, 250–300 clear sunny days andaverage solar radiation varying from 1460 to 2555 kWh/(m2 a)across the country [9], the government has taken steps to utilisethis solar potential with an installed capacity of 28 GW, until endof March 2019 and aggressive future targets [10, 11, 12]. The vastcoastline of India provides perfect conditions for wind powerinstallations, with the potential mainly concentrated in the states ofTamil Nadu, Gujarat, Karnataka, Maharashtra and Rajasthan.While the current total wind capacity is around 34 GW [10], thepotential is estimated at around 2000 GW [13, 14]. Tamil Nadu isthe leading state in terms of wind power installations [10].

However, the major drawback of the above technologies is thatelectricity can be produced only during certain intervals. For

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example, when the Sun is shining during the day and strong windsin the evening and night or the monsoon season for the specificcase of India. Hybrid projects may reduce variability to someextent and power can be generated at night and even in themonsoon months [15]. The Ministry of New and RE has released adraft policy for hybrid solar and wind energy projects [16]. While,at a lower penetration of variable renewable resources, thevariability of power generation can be effectively managed byramping up conventional fossil fuel generators, but for a fully RE-based system having a major share of solar and wind energies, thispresents a huge hindrance [17, 18, 19, 20].

On the other hand, increasing flexibility of the transmissionlines [21], adding storage capacity and power-to-gas flexibility tothe energy system [22, 23] and complementarity of wind and solar[22], would help mitigate the variability of solar and windresources. Various studies have shown that a 100% RE-basedsystem is possible for India. While TERI [24] puts forward that

such a scenario is desirable for India; however, it maintains thatfinancial and technical policies should be in proper order to makesuch a scenario realistic. On the other hand, according to Röbenand Köhler [25], a 100% RE scenario is feasible and more efficientthan the current energy system, while Lawrenz et al. [26] concludethat it is technically possible to supply energy for the power, heatand transportation sector entirely by renewables. According toGulagi et al. [27], a 100% RE-based system is technically andeconomically feasible on an hourly resolution [19, 27, 28] and alsofor countries in the South Asian Association for RegionalCooperation [29], with the cost structure less than the currentsystem based on fossil fuels. According to these studies, a fullyrenewable electricity system for India will be based mainly onsolar photovoltaic (PV) complemented by other RE technologies.However, these studies do not address in detail an importantquestion: ‘How will a solar PV-dominated electricity systemperform during the monsoon season’?

The onset of monsoon is from the southwest of India, and thenit travels into the western, eastern, northeastern and northernregions. The increase in cloud cover follows this path; as a result,

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solar resource availability varies between the different regionsbased on the position of the monsoon. Strong southwesterly windsaccompany the arrival of the monsoon, giving rise to peak windresources, particularly in the southern and western regions. On theother hand, solar resource is low during the monsoon season, dueto the presence of cloudy weather [30]. The decrease in powerproduction from solar PV in a particular region affected by themonsoon can pose considerable challenges for the stability of thepower grid. To balance the monsoon effect in a 100% RE system,wind energy will play a vital role in complementing the deficit insolar PV generation (Figs. 1a and b), along with additionalflexibility options provided by transmission grids, storagetechnologies in particular batteries and hydropower.

Not many studies have shown a fully RE-based scenario forIndia on an hourly resolution with storage technologies andtransmission grids. Furthermore, none of them has a special focuson the energy system analysis during the monsoon season. A studyby the National RE Laboratory [31] touches on the aspect ofmonsoon season and transmission grid utilisation, but does notdwell into the impacts in detail. Also, the study is limited to theyear 2022, taking into account the governments RE targets.According to this paper, curtailment is highest in the monsoonmonths compared with non-monsoon months, and curtailment canbe reduced in the regions generating highest RE by evacuating thepower generated via additional transmission grids and integratingthe different regions.

This paper is a first of its kind to analyse the effects of themonsoon season on a fully RE system. In the first step, this paperanalyses the complementarity provided by wind energy to thedecrease in solar PV. In the second step, we analyse the role of thetransmission grid in evacuating power from different regions to themonsoon-affected regions. Thus, reducing curtailment in theseregions. It is acknowledged that hydropower and storagetechnologies provide some level of flexibility to the system.However, these are not discussed in this paper as Gulagi et al. [32]describe the role of hydropower and storage technologies in themonsoon period in greater detail. Historically, India has relied oncoal and hydropower for supplying electricity to most of its regionsand the monsoon season had less impact on the supply side.However, a rapidly evolving power sector with increasing shares ofrenewables compels energy planers and other stakeholders toconsider the impacts of seasonal variations such as the monsoonson power systems with high shares of renewables.

This paper is organised as follows: Section 2 provides themethodology, the input data and the technologies used for thesimulations. This is followed by the assumptions and description ofthe power scenario used for the simulations in Section 3. All thetechnical and financial assumptions are provided in Section 4.Section 5 presents the results and discussion. Finally, conclusionsare drawn in Section 6.

2 Methods and input data

The model with its equations and constrains used for this paperhave been described in detail previously by Bogdanov et al. [28]and Gulagi et al. [19]. The following section gives a briefdescription of the main optimisation function and the constraints.

The model is based on linear optimisation and the mainconstraint is that total power generation should be equal to the totalpower demand in that particular hour for the selected year, whereasthe main objective function is to minimise the total annual energysystem costs, calculated as a sum of the costs of installedcapacities, energy generation and generation ramping of thedifferent technologies. For every 5 year intervals from 2015 to2050, the model optimises the least-cost solution. The equations forthe objective function (1) and the main constraint are given below(2):

min ∑r = 1

reg∑t = 1

techCAPEXt crft + OPEXfixt instCapt, r

+OPEXvart Egen, t, r + rampCostt totRampt, r

(1)

CAPEXt is the capital cost of each technology, crft is the capitalrecovery factor for each technology, OPEXfixt is the fixedoperational cost for each technology, OPEXvart is the variableoperational cost for each technology, instCapt,r is the installedcapacity in a region, Egen,t,r is the electricity generation by eachtechnology, rampCostt is the ramping cost of each technology andtotRampt,r is the annual total power ramping values for eachtechnology. The target function was applied in time steps of 5 yearfrom 2015 to 2050

∀h ∈ 1, 8760 ∑t

techEgen, t , h + ∑

r

regEimp, r , h + ∑

t

storEstor, disch ,

h = Edemand , h + ∑r

regEexp, r , h + ∑

t

storEstor, ch) , h + Ecurt , h

(2)

It is defined for every hour of a year in a particular region,electricity generation from all the technologies (Egen,t), importedelectricity from the regions (Eimp,r) and electricity from storagedischarge (Estor,disch) should be equal to the total demand for anhour (Edemand), electricity exported to other regions (Eexp,r),electricity for charging storage technologies (Estor,ch) and curtailedelectricity (Ecurt). The other abbreviations used in this equation arehours (h), technology (t), all technologies used in modelling (tech),sub-region (r) and all sub-regions (reg).

The other two important constraints applied were:

• The RE-installed capacity cannot grow by more than 20% of thetotal power generation capacities for each 5 year time step toavoid the disruption of the power system.

• No new nuclear or fossil fuel capacities can be installed after2015, except gas turbines, which can utilise synthetic gas or bio-methane.

All the applied technologies from electricity generation, storageoptions used, bridging technologies and transmission of electricitycan be seen in Fig. 2.

3 Grid structure and scenarioIndia was divided into ten sub-regions based on the populationdistribution, consumption of electricity and the grid structure as inFig. 3.

The power scenario [19] was studied for the analysis of theIndian energy system during the monsoon period. In this scenario,the energy systems of the different regions are interconnected.

Fig. 1 Solar PV generation(a) Solar profile on an hourly basis for India, (b) Wind profile on hourly basis for India

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2 IET Renew. Power Gener.© The Institution of Engineering and Technology 2019

4 AssumptionsAll the technical and financial assumptions related to the modelcan be found in the supplementary material of Gulagi et al. [19].

5 Results and discussionAccording to Gulagi et al. [19, 27], a power system based on fullyRE is the least-cost solution, and the system can overcomehindrances created during the monsoon months.

The structure of the system concerning power generationtechnologies, storage technologies and transmission grids wasanalysed in detail, and the following sub-sections will explain indetail the roles of power generation, storage technologies andtransmission grids in the monsoon and non-monsoon periods.

5.1 Complementarity of solar and wind generation in 2050

The total annual generations from solar PV and wind in 2050 are6000 and 415 TWh, respectively. These two RE sources contributeto almost 92% of the total electricity generation. Fig. 4 shows themonthly solar and wind generation in the year 2050 for the powerscenario. Solar generation is highest during March, April and May,which are also the summer months. While generation is at itslowest during the monsoon months of June, July, August andSeptember. On the contrary, wind generation is seasonal, and thepeak generation is observed during the monsoon period. Thelowest generation of electricity from solar is seen in July when themonsoon is at its peak in most parts of India. The highestgeneration from solar is observed in March, April and May whensummer is at its peak in most parts of India.

Owing to cloudy and rainy weather in the monsoon period(June–September), a decrease in the solar energy output wasobserved for all the regions. The decrease in solar energy output is

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dependent on a particular region; some regions that were affectedthe most by the monsoon saw a steep decrease in solar energyoutput and vice versa. The total power generation in the monsoonmonths from solar PV decreases by almost 14% in comparisonwith non-monsoon months. The regions India-West (IN-W), India-Central West (IN-CW) and India-Central South (IN-CS) are themost affected by the monsoon season with a decrease of 19, 34 and23%, respectively. On the other hand, regions India-Northwest (IN-NW), India-South (IN-S) and India-Central-East (IN-CE) seem tobe least affected by monsoon season with a decrease of 4, 5 and5%, respectively.

It was observed that the monsoon months (June–September)produce 62% of the total wind energy generated in India whilerepresenting only one-third period of the year. The regions of IN-W, Central West, Central South and the South regions producemore than 95% of the total wind energy generated. The electricitygenerated from wind energy particularly picks up in the regions ofCentral West and Central South. The coastal and some inlandregions of Gujarat, Maharashtra, Kerala and Tamil Nadu have thebest wind potential of all the sites available across India. The abovefindings are in agreement with Solomon et al. [22, 33], wherein thesolar–wind complementarity analyses were done for Israel andCalifornia, and Gerlach et al. [34] for global–local resolution.Here, the authors conclude that complementarity has multiplebenefits such as stable high share RE system and grid.Complementarity provides a fully RE system to function withouthindrances.

5.1.1 Analysis on a regional level: Significant variation of windgeneration exists across the regions in India. The southern andwestern regions are expected to install and generate most of thewind energy in India due to the availability of excellent windresources. This can be observed in the current-installed capacitiesof wind, which are concentrated in these regions. In comparison,the solar resource is well-distributed all over India, except the

Fig. 2 Block diagram of the look-up table energy system model [17]

Fig. 3 Ten sub-regions of India and grid interconnection between them

Fig. 4 Monthly electricity generation from solar PV and wind in 2050across India for the power scenario


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Northeast region. For regional analysis, two regions are selectedthat have the following characteristics:

• A region where PV generation decreases the most and wherewind generation is the highest in the monsoon period: IN-CW.

• A region where PV generation is least affected by the monsoonperiod: IN-S.

The dispatches of IN-CW and IN-S in a monsoon week can beobserved from Figs. 5 and 6, respectively. It can be observed forthe region Central West that the decrease in the solar PV output inthe initial hours of the week is effectively complemented by anincrease in electricity generation from wind. If solar is available,wind generation decreases as seen from the later hours of the week.As solar PV is the least-cost generation source, the system firstutilises all the available energy from solar, and if wind is availablein those hours it utilises wind, and the remaining energy isimported from neighbouring regions to satisfy the demand. Windovercomes the decrease in solar PV output for the Central Westregion in the monsoon period.

For the region IN-S, which is least affected by the monsoonperiod, it is observed that the solar PV output is constant for allhours of the week with even export of excess electricity in thesehours. Such regions help to balance the demand of theneighbouring regions with whom they are connected bytransmission lines via electricity exports in the monsoon season.

Solar being the major energy source for India in 2050,curtailment is reduced in all the regions during the monsoon periodwith an overall decrease in solar generation in most parts of India.The highest curtailment is observed in the summer months as thisis the peak duration for solar generation. From the onset of themonsoon season, curtailment decreases drastically in most of theregions and goes down to zero in almost all the regions, except IN-S. As seen earlier, this is the region that is least affected bymonsoon and the decrease in solar PV generation is the lowest. Inthe monsoon months, increase in electricity generated by windsupports the system even when the electricity generated from solarPV decreases.

Fig. 5 Dispatch for the region IN-CW in a monsoon week in 2050

Fig. 6 Dispatch for the region IN-S in a monsoon week in 2050


5.2 Role of storage technologies

A fully RE system for India is based on a solar PV–battery hybrid,with batteries (prosumer and system) contributing to almost 90% ofthe total storage output and the remaining 10% from other storagetechnologies [19]. Gas storage, which is utilised as long-termstorage, contributes 7% of the total storage output [19].

In the monsoon period, battery output is 85% of the totalstorage output in comparison with 92% in the non-monsoon period.The reduced solar resource availability contributes to less energystored in the batteries since it is utilised as short-term storage thatperfectly complements solar availability and discharge in the night-times.

One interesting observation, which was made, is the increase inoutput of stored gas to produce electricity via combined cycle gasturbines (CCGTs). An increase of almost 10% is observed in thegas output in the monsoon period. CCGT plants can be ramped upto provide electricity in the night-times and periods of low solarradiation. From Fig. 7, it can be observed that gas storage is fullycharged before the start of the monsoon season and startsdischarging to cover demand in the monsoon months and fullydischarged until the monsoon is over. The relative utilisation of thestorage technologies in the monsoon period was 30% incomparison with the non-monsoon period, where it was 37%.Figs. 8a and b give the relative storage utilisation in all the sub-regions of India. While in the monsoon season, the utilisation ofstorage technologies decreases, still, storage technologies play animportant role in a 100% RE system in India, as found by Lawrenzet al. [26].

5.3 Role of transmission grids

In a fully RE system, there are a lot of import and export ofelectricity between the regions. Some regions act as net importersof electricity due to huge demands that cannot be satisfied by localgeneration, higher costs of primary generation and flexibilityprovided by different renewable power generation sources in otherregions. Transmission grids are important as they help to balancethe power demands in the different regions and decrease the needfor storing electricity since it can be cost-effective to importelectricity rather than storing it for later usage.

The net electricity is drawn from the grid to satisfy therespective demand increases in the monsoon period. In themonsoon period, the net electricity utilised from the grid was 6.2%in comparison with 4.9% in the non-monsoon period. The netimports and exports for all regions in India are 338 and 360 TWh,respectively. However, some regions are importing more than theothers are, for example, IN-CW, IN-W and IN-CS are the largestimporters of electricity. For these regions, the costs of primarygeneration are higher than the neighbouring regions with whichthey are connected and have high electricity demand. From Fig. 9,the imports and exports for all regions according to months of theyear can be observed.

In the monsoon period, the net import and export are 130 and137 TWh, respectively, representing about 38% of the total netelectricity transfer. It can be seen that during the monsoon period,which represents only one-third of a year, there is a lot of transferof electricity between the regions due to overall reduction in themajor source of electricity generation for India, which is solar.

5.3.1 Analysis on a regional level: From Fig. 9, it is seen thatthe imports and exports increase in some regions during the monthsof the monsoon. The region of IN-W has its peak imports in Juneand overall higher imports in the monsoon months than the non-monsoon months. As this region is one of the most affected by themonsoon with a decrease in solar PV output of 19%. This regionhas good potential for wind energy generation. However, theincrease in wind output is not enough to satisfy the total electricitydemand in the region. Therefore, importing electricity fromneighbouring regions benefits the IN-W region and decreasesoverall cost of the system.

The region of IN-S is a net exporting region, and it can be seenwith the increase of exports in the monsoon period. This region isblessed with good solar as well as wind resources. As this region isnot affected by the monsoon and the decrease in solar PV output isone of the lowest in the country. The wind output is increasedconsiderably so that the excess electricity is exported to IN-CS.The energy flow in one of the transmission lines is shown inFig. 10. The India-Eastern (IN-E) region imports electricity mainlyfrom the Central-East (IN-CE) region.

Fig. 7 Hourly state-of-charge profile of gas storage for India in 2050, forthe power scenario [19]

Fig. 8 Relative storage utilisation(a) Utilisation of storage technologies in the monsoon months for the power scenarioin 2050 [19], (b) Utilisation of storage technologies in the non-monsoon months forthe power scenario in 2050 [19]


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The positive numbers indicate imports and negative exports ofelectricity in the transmission lines. In the monsoon period, exportof electricity takes place for most hours in a day from the regionIN-CE due to solar resource unavailability in the region IN-E. Thisis also observed in Fig. 9 (imports). In the region IN-E, over 90%of the power generated is by solar, and this region does not havegood wind resource. Therefore, the exported electricity is useddirectly to satisfy the daytime demand or stored to satisfy the night-time load. During the non-monsoon months, electricity is exportedduring the daytime by IN-CE, which is consumed directly or storedin gas storage in the IN-E region.

To satisfy its demand, the IN-E region has to import electricityfrom IN-CE. This example shows how the system balances itselfdue to transmission grids in the monsoon months. The gridutilisation of the region IN-W increases in the monsoon period.This region has solar PV as the major power generation source andcomplemented by wind power, as this region is situated in one ofthe best wind sites in India having good wind potential all yearround. However, in the monsoon months, the demand cannot befulfilled by the available renewable resources due to the decreasein solar resource availability. Therefore, this region importselectricity from the IN-CW region, where wind energy is available,which can be seen from Fig. 11. From 4000 to 6500 h, the IN-Wregion imports wind energy from IN-CW to satisfy its powerdemand in the monsoon period.

The regions that are least affected by the monsoon and with aslight decrease in solar PV electricity production support the otherregions that are strongly affected, through transmitting electricityvia interconnected grids. A perfect example of this is the regions ofIN-NW and IN-W, as shown in Fig. 12. The region IN-NW is leastaffected by the monsoon, as major parts of the area consist of thedesert, where the solar conditions are almost constant all yearround with a slight decrease during the monsoon period. Incomparison, IN-W is most affected by the monsoon with electricityfrom solar PV decreasing by almost 19% in comparison with thenon-monsoon period. The region IN-W imports electricitygenerated by solar PV directly daily from IN-NW and more so inthe monsoon period with the absolute value of imports increasing(see Fig. 12). The same can be observed for the region IN-S, whichis least affected by the monsoon and is one of the largest exportersof electricity. The export of solar PV-generated electricity to IN-CSis daily in the noon and afternoon hours. For the regions, IN-NWand IN-S batteries are charged daily in the daytime and dischargedto satisfy the local demand or sometimes transmitting electricityvia grids to the other regions.

The regions of IN-NW and IN-S are the top two exporters ofelectricity amongst the ten regions. In the monsoon period, thesetwo regions combined export about 43% of the total electricity in2050. The exported electricity is mainly solar PV generated, as it isthe cheapest source for electricity and is abundantly available. Tominimise the overall cost of the system, it is more cost-effective to

export electricity from PV than wind. For IN-NW, the electricitygenerated from wind is negligible, and this further proves thatelectricity from solar PV is exported. Also, by utilising batteries toexport power even during the night-times to other regions forbalancing the load in the monsoon period in a cost-effective way.

The net energy transfer between the ten regions for a fully REsystem in 2050 is 678 TWh. For the monsoon period, the netenergy transfer is 250 TWh and for the non-monsoon period it is428 TWh. Fig. 13 gives an overview of the imports and exportsbetween the different regions in the monsoon and non-monsoonperiods. In Fig. 13, the thickness of the flow indicates the amountof electricity exchanged between the regions in TWh. The exporterregion ribbons and the flows have the same colour. For example,the blue ribbon of IN-S, an exporting region, extends a blue flow ofexport to IN-CS, a net importing region. Interesting observationscan be made from Fig. 13 in terms of major importing andexporting regions. IN-NW is a major exporting region in themonsoon period with exports to the regions of IN-W and IN-UP.

Fig. 9 Imports (top) and exports (bottom) for the ten regions in India on amonthly scale in 2050

Fig. 10 Grid profiles for the power scenario in 2050 for IN-CE (left) and IN-E (right). Import (+) and export (−)


As the effects of the monsoon on this region are the lowest in termsof solar power production, this region exports electricity to theregions impacted most by the monsoon. In the monsoon period,IN-W is a major importing region, importing from IN-CW and IN-NW. However, in the non-monsoon period, IN-W exportselectricity to IN-CW, while importing from IN-NW.

6 ConclusionA fully renewable electricity system for India is possible in 2050 inan hourly resolution. Besides, the proposed system can effectivelyhandle the decreased solar power generation during the monsoonseason by effectively utilising transmission grids and increasedwind power availability.

The reduced power generation from solar PV in the monsoonperiod can be effectively complemented by an increase in powergeneration from wind, in some regions. Total power generation

from wind in the monsoon period is 62% of the total wind powergenerated in India. The region of IN-CW, where the windgeneration increases considerably in comparison with the otherregions, satisfies its demand and exports excess wind energy.

The interconnection of regions via transmission grids helps tobalance the power demand in regions that are most cost-effectivelyaffected by the monsoon. Total imports to satisfy the demand in themonsoon period increases by 1.3% in comparison with the non-monsoon period. It is observed that in the monsoon period, whichrepresents only one-third of a year, the net electricity transferhappening in the grids is 38% of the annual net electricity transfer.The energy flow between the regions of IN-E and IN-CE clearlyshows an increase in imports during the monsoon period by IN-E,due to the decrease in its solar energy production. The decrease insolar PV availability in the region IN-W is compensated byincreasing its imports from IN-CW and IN-NW. The electricity

Fig. 11 Grid energy flows and wind energy generation on an hourly basis for the power scenario in 2050. The blue line is wind energy generation in the IN-CW region. The red and green lines are the annual import and export by IN-CW and IN-W, respectively

Fig. 12 Grid profiles for the power scenario in 2050 for IN-NW (left) and IN-W (right). Import (+) and export (−)


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exported from IN-CW mainly being wind and solar and from IN-NW.

These results prove that RE options are the most competitiveand least-cost solution for achieving a zero GHG emission-basedelectricity system, even in the monsoon season without utilisingbalancing power based on fossil fuels.

7 AcknowledgmentsThe authors gratefully acknowledge the public financing of Tekes,the Finnish Funding Agency for Innovation, for the Finnish SolarRevolution project under the number 880/31/2016. The first thankFortum Foundation for the valuable scholarship.

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Fig. 13 Electricity exchange for the monsoon period (top) and non-monsoon period (bottom) among the ten regions in 2050 for the power scenario. Thethickness of the flow indicates the amount of electricity exchange denoted as TWh


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gulagi ashish, ram manish, breyer christian

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